US9192383B2 - Circular stapling device including buttress material - Google Patents

Abstract

An anvil assembly includes a circular anvil head that supports a crush ring, an anvil cap that supports an o-ring, and a circular anvil buttress member. The cap connects to the head and is movable relative to the head between approximated and unapproximated positions. The crush ring is spaced from the cap when the cap is in the approximated position and movable into engagement with the cap to move the cap to the unapproximated position. The buttress member includes a body portion and an extension portion. The body portion is supported on the head and the extension portion is secureable between the o-ring and the head when the cap is in the approximated position. The extension portion is releasable from between the o-ring and the head when the cap is disposed in the unapproximated position so that the body portion separates from the head.

Description

TECHNICAL FIELD

The present disclosure relates to surgical stapling devices and, more particularly, to structures and methods for removably attaching buttress material to circular surgical stapling devices for use in anastomosis procedures.

BACKGROUND

Fasteners have been used to replace suturing when joining various body structures such as, for example, the bowel or bronchus. Surgical stapling devices employed to apply these fasteners are generally designed to simultaneously cut and seal tissue to reduce the time and risks involved with anastomosis procedures.

Circular surgical stapling devices are employed by surgeons to sequentially or simultaneously apply one or more surgical fasteners, e.g., staples or two-part fasteners, to body tissue for the purpose of joining segments of body tissue together and/or for the creation of anastomoses. Circular surgical stapling devices generally include an annular fastener cartridge assembly that supports a plurality of annular rows of fasteners, an annular anvil assembly operatively associated with the fastener cartridge assembly which provides a surface against which the fasteners are formed upon a firing of the circular stapling device, and an annular blade for cutting tissue.

For most procedures, the use of bare fasteners, with the fasteners in direct contact with the patient's tissue, is generally acceptable. The integrity of the tissue will normally serve to prevent the fasteners from tearing out of the tissue and compromising the sealing before healing has occurred. However, in some surgical operations buttress materials are employed by surgeons in combination with circular stapling devices to bridge, repair and/or reinforce tissue defects within a patient. In particular, buttress materials reduce the trauma suffered by the patient, reduce the instances of leakage, reduce the instances of bleeding, and create a relatively strong bond between adjacent body tissues.

Accordingly, there is a need for reliably and removably attaching buttress material onto a circular stapling device so that the buttress material does not interfere with the operation of the device, remains on the device until after the fasteners are fired, and is convenient and easy to install and use.

SUMMARY

According to one aspect, a circular stapling device includes a handle assembly, an elongate body that extends from the handle assembly, and an end effector mounted on a distal end of the elongate body and including a cartridge assembly and an anvil assembly.

The anvil assembly includes a circular anvil head that supports a crush ring, an anvil cap that supports an o-ring, and a circular anvil buttress member. In embodiments, the o-ring is formed of an elastomeric material including nitrile.

The anvil cap connects to the anvil head and is movable relative to the anvil head between an approximated position and an unapproximated position. The crush ring is spaced from the anvil cap when the anvil cap is disposed in the approximated position and movable into engagement with the anvil cap to move the anvil cap to the unapproximated position. The anvil cap defines a groove in a bottom surface of the anvil cap and the o-ring is secured within the groove. The o-ring is disposed in a compressed condition when the anvil cap is disposed in the approximated position and an uncompressed condition when the anvil cap is disposed in the unapproximated position.

The anvil cap includes a snap feature and the anvil head defines a first recess and a second recess. The snap feature is selectively positionable within one of the first recess and the second recess. The snap feature is positionable within the first recess when the anvil cap is disposed in the approximated position and is positionable within the second recess when the anvil cap is disposed in the unapproximated position. The first recess and the second recess are separated by a ramped partition. The snap feature cams over the ramped feature as the anvil cap moves from the approximated position to the unapproximated position. The snap feature flexes outwardly from the first recess as the snap feature cams over the ramped partition and flexes inwardly into the second recess after camming over the ramped partition. The snap feature maintains the anvil cap secured to the anvil head when the snap feature is disposed in the second recess.

The circular anvil buttress member includes a body portion and an extension portion that extends from the body portion. The body portion is supported on a tissue engaging surface of the anvil head. The extension portion is secureable between the o-ring and the anvil head when the anvil cap is disposed in the approximated position. The extension portion is releasable from between the o-ring and the anvil head when the anvil cap is disposed in the unapproximated position so that the body portion separates from the tissue engaging surface of the anvil head. The extension portion includes one or more tabs. The o-ring is compressed against the one or more tabs when the anvil cap is disposed in the approximated position to maintain the body portion supported on the tissue engaging surface of the anvil head.

In another aspect, then anvil assembly includes a circular anvil head that supports a crush ring, and anvil cap that connects to the anvil head and supports an o-ring, and a circular anvil buttress member.

The anvil cap is movable relative to the anvil head between an approximated position and an unapproximated position. The crush ring is spaced from the anvil cap when the anvil cap is disposed in the approximated position and movable into engagement with the anvil cap to move the anvil cap to the unapproximated position. The anvil cap defines a groove in a bottom surface of the anvil cap. The o-ring is secured within the groove. The o-ring is disposed in a compressed condition when the anvil cap is disposed in the approximated position and in an uncompressed condition when the anvil cap is disposed in the unapproximated position. In embodiments, the o-ring is formed of an elastomeric material including nitrile.

The anvil cap includes a snap feature and the anvil head defines a first recess and a second recess. The snap feature is selectively positionable within one of the first recess and the second recess. The snap feature is positionable within the first recess when the anvil cap is disposed in the approximated position and is positionable within the second recess when the anvil cap is disposed in the unapproximated position. The first recess and the second recess are separated by a ramped partition. The snap feature cams over the ramped feature as the anvil cap moves from the approximated position to the unapproximated position. The snap feature flexes outwardly from the first recess as the snap feature cams over the ramped partition and flexes inwardly into the second recess after camming over the ramped partition. The snap feature maintains the anvil cap secured to the anvil head when the snap feature is disposed in the second recess.

The circular anvil buttress member includes a body portion and an extension portion that extends from the body portion. The body portion is supported on a tissue engaging surface of the anvil head. The extension portion is secureable between the o-ring and the anvil head when the anvil cap is disposed in the approximated position. The extension portion is releasable from between the o-ring and the anvil head when the anvil cap is disposed in the unapproximated position so that the body portion separates from the tissue engaging surface of the anvil head. The extension portion includes one or more tabs. The o-ring is compressed against the one or more tabs when the anvil cap is disposed in the approximated position to maintain the body portion supported on the tissue engaging surface of the anvil head.

According to yet another aspect, the present disclosure is directed to a method for releasing an anvil buttress member from an anvil assembly of a circular stapling device. The method includes the step of providing a circular stapling device including an elongate member having an end effector mounted on a distal end of the elongate body. The end effector includes an anvil assembly that includes an anvil head and an anvil cap that supports an o-ring. The anvil assembly includes an extension portion of an anvil buttress member secured between the o-ring and the anvil head so that a body portion of the anvil buttress member is supported on a tissue engaging surface of the anvil head. The method involves moving the o-ring relative to anvil head to release the anvil buttress member from the anvil assembly. Another step includes moving a crush ring supported on the anvil head into engagement with the anvil cap to move the o-ring relative to the anvil head. Yet another step involves spacing the o-ring and the anvil head relative to one another in response to engagement of the crush ring with the anvil head to provide a gap between the o-ring and the anvil head sufficient to enable the extension portion of the anvil buttress member to be released from between the o-ring and the anvil head.

Other aspects, features, and advantages will be apparent from the description, drawings, and claims.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and, together with a general description of the disclosure given above and the detailed description given below, serve to explain the principles of the disclosure, wherein:

FIG. 1 is a perspective view of a circular surgical stapling device according to the present disclosure;

FIG. 2 is an enlarged top perspective view of an embodiment of an anvil assembly and a shaft member of the presently disclosed circular surgical stapling device;

FIG. 3 is a bottom perspective view of the anvil assembly and a portion of the shaft member;

FIG. 4 is a perspective view, with parts separated, of the anvil assembly and the shaft member;

FIGS. 5-6 are progressive cross-sectional views of the anvil assembly and a distal portion of the shaft member, each view showing the anvil assembly in a different configuration; and

FIG. 7 is a perspective view, with parts separated, of another embodiment of an anvil assembly.

DETAILED DESCRIPTION

As used herein, the term “clinician” refers to a doctor, a nurse, or any other care provider and may include support personnel. Particular embodiments of the present disclosure will be described herein with reference to the accompanying drawings. As shown in the drawings and as described throughout the following description, and as is traditional when referring to relative positioning on an object, the term “proximal” refers to the end of the device that is closer to the clinician and the term “distal” refers to the end of the device that is farther from the clinician. In the following description, well-known functions or constructions are not described in detail to avoid obscuring the present disclosure in unnecessary detail.

Referring initially toFIG. 1, a circular surgical stapling device for use with a buttress material is disclosed herein and is generally designated as10. In embodiments, thesurgical stapling device10 is adapted for reuse and, in certain embodiments, thesurgical stapling device10 is adapted for a single use and can be disposable.

Thecircular stapling device10 includes ahandle assembly20, a tubularelongate body30, and anend effector40. Theend effector40 can be provided as a removable and replaceable assembly. Thehandle assembly20 includes a rotatable advancingmember22 and apivotable trigger member24 that are operatively coupled to any number of drivers supported by thesurgical stapling device10 to effectuate a firing of thesurgical stapling device10. Theelongate body30 extends distally from a distal end portion of thehandle assembly20 to a proximal end portion of theend effector40 so that theelongate body30 is disposed between thehandle assembly20 and theend effector40. In some embodiments, theelongate body30 has a linear shape along the length of theelongate body30, and in certain embodiments, theelongate body30 has a curved shape along the length of theelongate body30.

Theend effector40 includes afastener cartridge assembly100, ananvil assembly200, and ashaft300. Theshaft300 includes a proximal end portion that is secured to thefastener cartridge assembly100 and a distal end portion that is secured to theanvil assembly200. In embodiments, thefastener cartridge assembly100 and/or theanvil assembly200 may be replaced and thecircular stapling device10 may be reused. In embodiments, theend effector40 supports a knife assembly with a substantially cylindrical knife400 (FIG. 6) adapted to cut tissue.

Reference may be made to U.S. Pat. No. 5,915,616 to Viola et al. and commonly owned U.S. Patent Application Publication No. 2011/0174099, the entire contents of which are incorporated herein by reference, for a detailed discussion of the construction and operation of exemplary circular stapling devices.

Turning now toFIGS. 2-6, theanvil assembly200 includes acircular anvil head210, an o-ring215, ananvil cap220, a circular anvil buttressmember230, acrush ring member240, ananvil plate250, and aring assembly260.

With continued reference toFIG. 4, thecircular anvil head210 includes ahead body212 that supports thecrush ring member240, thering assembly260, and theanvil plate250. Thehead body212 has a connector214 that extends proximally from thehead body212 and is dimensioned to operatively couple to adistal end portion302 of theshaft300. The connector214 defines a pair ofopposed channels214a. One or moreengaging passages216 are defined by thehead body212 and extend through thehead body212. As shown inFIGS. 5-6, a distal surface of thehead body212 includes one or more rampedpartitions218 that separate afirst recess218aand asecond recess218bdefined on opposite sides of the rampedpartition218.

Referring again toFIG. 4, theanvil cap220 includes acap body222 that is supported on the distal surface of theanvil head210 so that the o-ring215 is positionable between thecap body222 and theanvil head210. In particular, thecap body222 defines anannular groove222awithin which the o-ring215 is dimensioned to be received. Thecap body222 includes one or moreengaging features224 and one or more snap features226 that extend proximally from thecap body222. Referring also toFIGS. 5-6, thesnap feature226 includes atooth226athat extends radially inwardly. The first andsecond recesses218a,218bof theanvil head210 are each dimensioned to receive thetooth226ato facilitate securement of theanvil cap220 to theanvil head210. Thecap body222 defines anopening228 dimensioned to enable thesnap feature226 to flex radially outwardly to permit theanvil cap220 to move relative to theanvil head210 between approximated and unapproximated positions.

Theanvil plate250 secures to the proximal surface of theanvil head210 and has anannular body252 that defines anopening254 therethrough. Theannular body252 has atissue engaging surface256 that defines a plurality offastener forming pockets256a. The plurality offastener forming pockets256ais arranged in an annular array about thetissue engaging surface256 of theannular body252.

The circular anvil buttressmember230 is selectively supported on theanvil plate250 and has anannular body portion232 and one ormore extension portions234 that extends radially from thebody portion232. Thebody portion232 is dimensioned to overly thetissue engaging surface256 of theanvil plate250 and defines acentral opening236 therethrough. Theextension portion234 includes a plurality of spaced aparttabs234athat extend radially outwardly about thebody portion232. The plurality of spaced aparttabs234aare selectively positionable between the proximal surface of theanvil cap220 and the distal surface of theanvil head210 to selectively secure theannular body portion232 against thetissue engaging surface256 of theanvil plate250 when theanvil cap220 is disposed in the approximated position. As described in greater detail below, theextension portion234 is releasable from the between theanvil cap220 and theanvil head210 when theanvil cap220 is moved to the unapproximated position so that thebody portion232 separates from thetissue engaging surface256 of theanvil plate250.

Thecrush ring member240 is supported on theanvil head210 and includes a generallyannular body242 having a plurality oftab members244 that secure to a proximal surface of theanvil head210 and extend from thebody242 at radially spaced locations along an outer surface of thebody242. Thecrush ring member240 is dimensioned to be spaced from the one or moreengaging features224 of thecap body222 when theanvil cap220 is disposed in the approximated position and movable into engagement with the one or moreengaging features224 to move theanvil cap220 to the unapproximated position. Theannular body242 defines anaperture246 therethrough that is dimensioned to receive the connector214 of thehead body212 when thecrush ring member240 is secured to theanvil head210.

As illustrated inFIG. 4, thering assembly260 is supported between theanvil head210 and theanvil plate250. Thering assembly260 includes a firstannular member270, a secondannular member280, and a thirdannular member290.

The firstannular member270 includes abody272 having aproximal surface272aand a distal surface272bwith acentral opening274 defined by aninner surface272cthat extends between theproximal surface272aand the distal surface272bof thebody272. Thebody272 includes a plurality of annularly spaced apartprojections276 that extend distally from the distal surface272bof thebody272. Eachprojection276 includes a pair ofopposed support arms276athat extend from theprojection276. Theopposed support arms276aare disposed substantially transverse to theprojection276.

The secondannular member280 includes abody282 having aproximal surface282aand adistal surface282bwith acentral opening284 defined by aninner surface282cthat extends between theproximal surface282aand thedistal surface282bof thebody282. Thebody282 includes a pair of opposed nubs286 that extend from theinner surface282cand are dimensioned to slide within thechannels214adefined in the connector214 of theanvil head210. Thebody282 includes a plurality ofledges288 extend from anouter surface282dof thebody282 and radially about theouter surface282dof thebody282.Adjacent ledges288 define apassage285 therebetween that is dimensioned to receive theprojections276 of the firstannular member270 such that theopposed support arms276aof theprojections276 are supported against theadjacent ledges288 on thedistal surface282bof the secondannular member280 when the first and secondannular members270,280 are secured together. The portion of theouter surface282dof thebody282 positioned proximally of theledges288 is dimensioned to be seated within thecentral opening274 defined by the firstannular member270 when the first and secondannular members270,280 are secured together. As shown inFIGS. 5 and 6, at least portions of the proximal surfaces of the first and secondannular members270,280 are substantially aligned when the first and secondannular members270,280 are secured together.

The thirdannular member290 includes abody292 having aproximal surface292aand adistal surface292bwith a central opening294 defined by aninner surface292cthat extends between theproximal surface292aand thedistal surface292bof thebody292. As shown inFIGS. 5 and 6, when the annular members of thering assembly260 are secured together, theinner surface292cof the thirdannular member290 radially surrounds an outer surface of theledges288 of the secondannular member280 and retains theprojections276 of the firstannular member270 within thepassages285 of the secondannular member280. In this regard, the distal surface272bof the firstannular member270 engages theproximal surface292aof the thirdannular member290 and at least portions of thedistal surface292bof the thirdannular member290 and thedistal surface282bof the secondannular member280 are disposed in substantial alignment and in contact with a proximal surface of thecrush ring240.

During operation of thesurgical stapling device10, theanvil assembly200 and thecartridge assembly100 are approximated by the actuation of advancingmember22 until theanvil assembly200 and thecartridge assembly100 are suitably clamped against tissue of a patient. Thetrigger member24 is then actuated to fire thesurgical stapling device10. Upon a firing of thesurgical stapling device10, the legs of the fasteners supported within thecartridge assembly100 are advanced through the clamped tissue and any buttress material clamped against tissue including the anvil buttressmember230 and any buttress material that may supported on the cartridge assembly. As the fasteners are distally advanced, the legs of the fasteners are formed by thefastener forming pockets256adefined in theanvil plate250 to secure the buttress material including the anvil buttressmember230 to the tissue.

Referring again toFIGS. 5-6, theknife400 is simultaneously or thereafter advanced into theanvil assembly200 to sever the clamped tissue and to advance into engagement with theproximal surface272aof the firstannular member270 of thering assembly260. Upon engagement with the firstannular member270, theknife400 distally drives theentire ring assembly260 toward theanvil cap220. Notably, as thering assembly260 is moved distally, the pair of opposed nubs286 of the secondannular member280 slide through thechannels214aofanvil head210 such that thering assembly260 drives thecrush ring member240 distally into engagement with the one or moreengaging features224 of theanvil cap220.

The distal movement of thecrush ring member240 into engagement with the one or moreengaging features224 of theanvil cap220 separates the proximal surface of thecap body222 of theanvil cap220 from the distal surface of thehead body212 of theanvil head210 so that the o-ring215 separates from theextension portions234 of the anvil buttressmember230. In particular, theteeth226aof the snap features226 cam against the rampedpartitions218 so that eachsnap feature226 flexes radially outwardly into theopening228 of thecap body222 from thefirst recess218aof thehead body212 to enable theanvil cap220 to separate from theanvil head210 as theanvil cap220 moves from the approximated position to the unapproximated position. After camming over the rampedpartitions218, theteeth226aof the snap features226 snap or flexes radially inwardly into thesecond recess218bof thehead body212 to maintain theanvil cap220 secured to theanvil head210. The separation of thecap body222 and thehead body212 creates a space or gap “G” between the proximal surface of thecap body222 and a distal surface of thehead body212 to free theextension portion234 of the anvil buttressmember230 from between theanvil head210 and the o-ring215 so that the anvil buttressmember230 is secured to the tissue independent of thesurgical stapling device10.

As illustrated inFIG. 7, an embodiment of an anvil assembly is generally referred to asanvil assembly500 and is substantially similar toanvil assembly200 and thus,anvil assembly500 is described herein only to the extent necessary to describe the differences in construction and operation of theanvil assembly500.Anvil assembly500 includes acircular anvil head210, an o-ring215, ananvil cap220, a circular anvil buttressmember230, acrush ring member240, and ananvil plate250. Notably,anvil assembly500 does not includering assembly260 and thus, when thecircular knife400 is advanced into theanvil assembly500 during operation, the blade of thecircular knife400 directly engages the proximal surface ofcrush ring member240 to drive thecrush ring member240 distally into engagement with theanvil cap220. In particular, as noted above, the distal movement of thecrush ring member240 into engagement with the one or moreengaging features224 of theanvil cap220 separates the proximal surface of thecap body222 of theanvil cap220 from the distal surface of thehead body212 of theanvil head210 so that the o-ring215 separates from theextension portions234 of the anvil buttressmember230 to free the anvil buttressmember230.

Although a manually operated handle assembly is shown inFIG. 1, in any of the embodiments disclosed herein, the handle assembly can be powered by a motor and an external or internal power source. One or more drive shafts extending through the elongate body can drive the various functions (i.e., approximation, stapling and cutting) of the instrument.

In any of the embodiments disclosed herein, one or more of thecrush ring240 and parts of thering assembly260 could be eliminated. Furthermore, the circular knife may directly move theanvil cap220 above to release the buttress member.

Persons skilled in the art will understand that the structures and methods specifically described herein and illustrated in the accompanying figures are non-limiting exemplary embodiments, and that the description, disclosure, and figures should be construed merely as exemplary of particular embodiments. It is to be understood, therefore, that the present disclosure is not limited to the precise embodiments described, and that various other changes and modifications may be effected by one skilled in the art without departing from the scope or spirit of the disclosure. Additionally, it is envisioned that the elements and features illustrated or described in connection with one exemplary embodiment may be combined with the elements and features of another without departing from the scope of the present disclosure, and that such modifications and variations are also intended to be included within the scope of the present disclosure. Indeed, any combination of any of the presently disclosed elements and features is within the scope of the present disclosure. Accordingly, the subject matter of the present disclosure is not to be limited by what has been particularly shown and described.

Claims (20)

What is claimed is:

1. A circular stapling device, comprising:

a handle assembly;

an elongate body that extends from the handle assembly;

an end effector mounted on a distal end of the elongate body and including a cartridge assembly and an anvil assembly, the anvil assembly including:

a circular anvil head that supports a crush ring;

an anvil cap that connects to the anvil head, the anvil cap being movable relative to the anvil head between an approximated position and an unapproximated position, the crush ring being spaced from the anvil cap when the anvil cap is disposed in the approximated position and movable into engagement with the anvil cap to move the anvil cap to the unapproximated position, the anvil cap supporting an o-ring; and

a circular anvil buttress member including a body portion and an extension portion that extends from the body portion, the body portion supported on a tissue engaging surface of the anvil head, the extension portion being secureable between the o-ring and the anvil head when the anvil cap is disposed in the approximated position, the extension portion being releasable from between the o-ring and the anvil head when the anvil cap is disposed in the unapproximated position so that the body portion separates from the tissue engaging surface of the anvil head.

2. The circular stapling device ofclaim 1, wherein the anvil cap defines a groove in a bottom surface of the anvil cap, the o-ring being secured within the groove.

3. The circular stapling device ofclaim 1, wherein the o-ring is formed of an elastomeric material.

4. The circular stapling device ofclaim 3, wherein the elastomeric material includes nitrile.

5. The circular stapling device of1, wherein the o-ring is disposed in a compressed condition when the anvil cap is disposed in the approximated position, and wherein the o-ring is disposed in an uncompressed condition when the anvil cap is disposed in the unapproximated position.

6. The circular stapling device ofclaim 1, wherein the extension portion of the circular anvil buttress member includes at least one tab, the o-ring being compressed against the at least one tab when the anvil cap is disposed in the approximated position to maintain the body portion of the circular anvil buttress member supported on the tissue engaging surface of the anvil head.

7. The circular stapling device ofclaim 1, wherein the anvil cap includes a snap feature and the anvil head defines a first recess and a second recess, the snap feature being selectively positionable within one of the first recess and the second recess, the snap feature being positionable within the first recess when the anvil cap is disposed in the approximated position and being positionable within the second recess when the anvil cap is disposed in the unapproximated position.

8. The circular stapling device ofclaim 7, wherein the first recess and the second recess are separated by a ramped partition, the snap feature camming over the ramped feature as the anvil cap moves from the approximated position to the unapproximated position, wherein the snap feature flexes outwardly from the first recess as the snap feature cams over the ramped partition and flexes inwardly into the second recess after camming over the ramped partition, the snap feature maintaining the anvil cap secured to the anvil head when the snap feature is disposed in the second recess.

9. An anvil assembly, comprising:

a circular anvil head that supports a crush ring;

an anvil cap that connects to the anvil head and supports an o-ring, the anvil cap being movable relative to the anvil head between an approximated position and an unapproximated position, the crush ring being spaced from the anvil cap when the anvil cap is disposed in the approximated position and movable into engagement with the anvil cap to move the anvil cap to the unapproximated position; and

a circular anvil buttress member including a body portion and an extension portion that extends from the body portion, the body portion supported on a tissue engaging surface of the anvil head, the extension portion being secureable between the o-ring and the anvil head when the anvil cap is disposed in the approximated position, the extension portion being releasable from between the o-ring and the anvil head when the anvil cap is disposed in the unapproximated position so that the body portion separates from the tissue engaging surface of the anvil head.

10. The anvil assembly ofclaim 9, wherein the anvil cap defines a groove in a bottom surface of the anvil cap, the o-ring being secured within the groove.

11. The anvil assembly ofclaim 9, wherein the o-ring is formed of an elastomeric material.

12. The anvil assembly ofclaim 11, wherein the elastomeric material includes nitrile.

13. The anvil assembly ofclaim 9, wherein the o-ring is disposed in a compressed condition when the anvil cap is disposed in the approximated position, and wherein the o-ring is disposed in an uncompressed condition when the anvil cap is disposed in the unapproximated position.

14. The circular stapling device ofclaim 9, wherein the extension portion of the circular anvil buttress member includes at least one tab, the o-ring being compressed against the at least one tab when the anvil cap is disposed in the approximated position to maintain the body portion of the circular anvil buttress member supported on the tissue engaging surface of the anvil head.

15. The anvil assembly ofclaim 9, wherein the anvil cap includes a snap feature and the anvil head defines a first recess and a second recess, the snap feature being selectively positionable within one of the first recess and the second recess, the snap feature being positionable within the first recess when the anvil cap is disposed in the approximated position and being positionable within the second recess when the anvil cap is disposed in the unapproximated position.

16. The anvil assembly ofclaim 15, wherein the first recess and the second recess are separated by a ramped partition, the snap feature camming over the ramped feature as the anvil cap moves from the approximated position to the unapproximated position.

17. The anvil assembly ofclaim 16, wherein the snap feature flexes outwardly from the first recess as the snap feature cams over the ramped partition and flexes inwardly into the second recess after camming over the ramped partition, the snap feature maintaining the anvil cap secured to the anvil head when the snap feature is disposed in the second recess.

18. A method for releasing an anvil buttress member from an anvil assembly of a circular stapling device, comprising the steps of:

providing a circular stapling device including an elongate member having an end effector mounted on a distal end of the elongate body, the end effector including an anvil assembly, the anvil assembly including an anvil head and an anvil cap that supports an o-ring, the anvil assembly including an extension portion of an anvil buttress member secured between the o-ring and the anvil head so that a body portion of the anvil buttress member is supported on a tissue engaging surface of the anvil head; and

moving the o-ring relative to anvil head to release the anvil buttress member from the anvil assembly.

19. The method ofclaim 18, further comprising the step of moving a crush ring supported on the anvil head into engagement with the anvil cap to move the o-ring relative to the anvil head.

20. The method ofclaim 19, further comprising the step of spacing the o-ring and the anvil head relative to one another in response to engagement of the crush ring with the anvil head to provide a gap between the o-ring and the anvil head sufficient to enable the extension portion of the anvil buttress member to be released from between the o-ring and the anvil head.

Images